MK 318 ammo Info 5.56

Mk318 Mod 0
Following early engagements in Afghanistan and Iraq, U.S. Special Operations Forces reported that M855 ammunition used in M4A1 rifles was ineffective. In 2005, the Pentagon issued a formal request to the ammunition industry for “enhanced” ammunition. The only business that responded was the Federal Cartridge Company, owned by Alliant Techsystems. Working with the Naval Surface Warfare Center Crane Division, the team created performance objectives for the new ammo: increased consistency from shot to shot regardless of temperature changes, accuracy out of an M4A1 better than 2 minute of angle (2 inches at 100 yards, 3.9 inches at 300 yards), increased stopping power after passing through “intermediate barriers” like walls and car windshields, increased performance and decreased muzzle flash out of shorter barrel FN SCAR rifles, and costs close to the M855. The first prototypes were delivered to the government in August 2007. Increased velocity and decreased muzzle flash were accomplished by the type of powder used. The design of the bullet was called the Open Tip Match Rear Penetrator (OTMRP). The front of it is a hollow point backed up by a lead core, but the lead core only goes about halfway down the length of the bullet, while the rear half is solid brass. When the bullet hits a hard barrier, the front half of the bullet smooshes against the barrier, breaking it so the penetrating half of the bullet can go through and hit the target. With the lead section penetrating the target and the brass section following, it was referred to as a "barrier blind" bullet. Special Forces role in counter-terror operations allow them to follow certain law enforcement guidelines, so they could use hollow point rounds without violating the Hague Convention.[31][79]
Officially designated the Mk318 Mod 0 "Cartridge, Caliber 5.56mm Ball, Carbine, Barrier", and called SOST (Special Operations Science and Technology) ammunition, the 62-grain bullet fragments consistently, even out of a 10.5 in barrel. The lead portion fragments in the first few inches of soft tissue, then the solid copper rear penetrates 18 in of tissue (shown though ballistic gelatin) while tumbling. Out of a 14 in barrel, the Mk318 has a muzzle velocity of 2,925 fps.[31][79]
In February 2010, the U.S. Marine Corps adopted the Mk318 for use by infantry. To be fielded by an entire branch of the military, the round is classified as having an "open-tip" bullet, similar to the M118LR 7.62 NATO round. The SOST bullet uses a “reverse drawn” forming process. The base of the bullet is made first, the lead core is placed on top of it, and then the jacketing is pulled up around the lead core from bottom to tip. Conventional, and cheaper, bullets are made with the method of the jacket drawn from the nose to an exposed lead base. The reverse drawn technique leaves an open tip as a byproduct of the manufacturing process, and is not specifically designed for expansion or to affect terminal ballistics. The Pentagon legally cleared the rounds for Marine use in late January. The Marines fielded the Mk318 gradually and in small numbers. Initial studies showed that insurgents hit by it suffered larger exit wounds, although information was limited. SOST rounds were used alongside M855 rounds in situations where the SOST would be more effective.[31][79][80] In July 2010, the Marines purchased 1.8 million M855A1 Enhanced Performance Rounds in, addition to millions of Mk318 rounds in service, as part of its effort to replace its M855 ammo.
The MK 318 rounds use the new powder WC 842

Mk318 Mod 0
Following early engagements in Afghanistan and Iraq, U.S. Special Operations Forces reported that M855 ammunition used in M4A1 rifles was ineffective. In 2005, the Pentagon issued a formal request to the ammunition industry for “enhanced” ammunition. The only business that responded was the Federal Cartridge Company, owned by Alliant Techsystems. Working with the Naval Surface Warfare Center Crane Division, the team created performance objectives for the new ammo: increased consistency from shot to shot regardless of temperature changes, accuracy out of an M4A1 better than 2 minute of angle (2 inches at 100 yards, 3.9 inches at 300 yards), increased stopping power after passing through “intermediate barriers” like walls and car windshields, increased performance and decreased muzzle flash out of shorter barrel FN SCAR rifles, and costs close to the M855. The first prototypes were delivered to the government in August 2007. Increased velocity and decreased muzzle flash were accomplished by the type of powder used. The design of the bullet was called the Open Tip Match Rear Penetrator (OTMRP). The front of it is a hollow point backed up by a lead core, but the lead core only goes about halfway down the length of the bullet, while the rear half is solid brass. When the bullet hits a hard barrier, the front half of the bullet smooshes against the barrier, breaking it so the penetrating half of the bullet can go through and hit the target. With the lead section penetrating the target and the brass section following, it was referred to as a "barrier blind" bullet. Special Forces role in counter-terror operations allow them to follow certain law enforcement guidelines, so they could use hollow point rounds without violating the Hague Convention.[31][79]
Officially designated the Mk318 Mod 0 "Cartridge, Caliber 5.56mm Ball, Carbine, Barrier", and called SOST (Special Operations Science and Technology) ammunition, the 62-grain bullet fragments consistently, even out of a 10.5 in barrel. The lead portion fragments in the first few inches of soft tissue, then the solid copper rear penetrates 18 in of tissue (shown though ballistic gelatin) while tumbling. Out of a 14 in barrel, the Mk318 has a muzzle velocity of 2,925 fps.[31][79]
In February 2010, the U.S. Marine Corps adopted the Mk318 for use by infantry. To be fielded by an entire branch of the military, the round is classified as having an "open-tip" bullet, similar to the M118LR 7.62 NATO round. The SOST bullet uses a “reverse drawn” forming process. The base of the bullet is made first, the lead core is placed on top of it, and then the jacketing is pulled up around the lead core from bottom to tip. Conventional, and cheaper, bullets are made with the method of the jacket drawn from the nose to an exposed lead base. The reverse drawn technique leaves an open tip as a byproduct of the manufacturing process, and is not specifically designed for expansion or to affect terminal ballistics. The Pentagon legally cleared the rounds for Marine use in late January. The Marines fielded the Mk318 gradually and in small numbers. Initial studies showed that insurgents hit by it suffered larger exit wounds, although information was limited. SOST rounds were used alongside M855 rounds in situations where the SOST would be more effective.[31][79][80] In July 2010, the Marines purchased 1.8 million M855A1 Enhanced Performance Rounds in, addition to millions of Mk318 rounds in service, as part of its effort to replace its M855 ammo.
The MK 318 rounds use the new powder WC 842

I thought that S.F. had moved up to the 6.8SPC round that weighed 110 grains at about 2500fps. On paper it looks like a near ideal 200 yard round (close to 90% of all folks shot on the battlefield are less than 125 yards). The new .223 round looks interesting, but also expensive to manufacture.
gary

The 6.8 spc program was cancelled due to cost from switching from 5.56 brass to 6.8 spc brass

The 300 BLK is gaining some traction because it uses 5.56 brass and is very close in performance to the 7.62x39

Instead I suggest just adopt the 7.62x39

back in the late 1970's the Army and a couple private contractors were doing some experimenting with M16's that used .223 brass necked up to 6mm with an 85 grain bullet from Hornaday. Velocities were in the 2850fps to 2900fps, so they claimed. The idea was to get 150 grain bullet ballistics out of an Ar15 platform. Carter killed the project
gary